Military Aviation => Military Aircraft => Topic started by: Prowler on August 25, 2005, 12:28:54 AM

Title: Gripen quality???
Post by: Prowler on August 25, 2005, 12:28:54 AM
Hi there!

I was wondering if someone could give me a little info.

I am hopefully going to be flying for the SAAF (South African) soon, and we have recently acquired 29 Gripens. I've spoken to a couple of engineers here in SA that work for the SAAF and they  figured(or rather complained) that the Gripen is not appropriate for the weather conditions here in Africa. They claim that the engine  core temp. goes close to melting point (or something like that) and that the plane uses 20% excess thrust just to get the thing off the ground.

Is this really the case and how does the Gripens engine really cope in hot conditions?

Any replys would be great!

Title: Re: Gripen quality???
Post by: Viggen on August 25, 2005, 08:13:57 AM
Hi Prowler...I cant give you an answer at the  moment, but i will dig for some info and see what i can find.

But i find it kind of strange about the engine. It is an american General Electric F404-400 licensed by Volvo Flygmotor named RM12 here in Sweden. So they are completly rebuilt here in Sweden, never heard about any problems with the engine, have worked like clockwork.  :)
Title: Re: Gripen quality???
Post by: Webmaster on August 25, 2005, 09:01:58 AM
F404s are fitted to many aircraft, I can think of a few operated by hot countries, not sure if it is exactly the same. There are always complaints when new aircraft arrive, often blown up to big issues. I am sure there is some truth in there, especially on the take off. But if that's a problem, I don't know, maybe for the mechanics yes. Maybe with a few modifications it will work better in hot climates. But then again, perhaps the core of the complaint lies in the fact that it is a F404 engine, and not the powerful Atar's they got used to. I am no engineer and I am completely guessing here, but the F404 is a modern engine with new materials, maybe operating it at 'core temp' at close melting point is possible and no problem.

But, I'll put my money on Viggen at the moment, to do some research on this.  ;D
Title: Re: Gripen quality???
Post by: Viggen on August 25, 2005, 10:30:04 AM
Volvo Aero has also been responsible for improving the engine in a number of areas and reduced costs for the user dramatically. Among these changes, the company designed a new control system (FADEC), a new front frame and a new radial flame holder. The engine is also adapted to perform in world wide climatic conditions, from extreme cold to extreme heat.
To date, Volvo Aero has assembled 180 of a total of 225 RM12 engines on order to the Swedish Air Force.

The experience of the Swedish Air Force with the RM12 engine  is highly favorable. The total number of flight hours is nearly 50,000 and to date there have been no accidents or incidents related to engine problems.

The RM12 represents a new advance with regard to problem-free operations and maintenance for the user, superior to any military aircraft engine.

The RM12 engine is designed for a cost efficient use and features many operational advantages:

It does not require any expensive scheduled major engine overhaul.
The on condition maintenance philosophy is based on a modularly designed engine, the possibility to inspect the engine mounted in the aircraft – Engine Conditioning Monitoring (ECMS) and most of Line Replaceable Units (LRU) that are easily accessible and replaceable in the aircraft.
No adjustments or trimming are required after module or LRU replacement.
It is quick and easy to inspect the engine between flights. It takes less than four minutes for a preflight inspection of the engine before it is cleared for a new mission.
The engine can be replaced in the field in less than one hour, with just a few simple tools.
The engine is already recognized for its world-class reliability. 
In addition to South Africa, Hungary and the Czech Republic have decided to chose the Gripen. 

For more information, please contact
Magnus Bergström , Chief Engineer, Volvo Aero, +46 70 2200 101, or Björn Åstrand, Vice President Military Programs, +46 70 5690451, or Fredrik Fryklund, Corporate Communications, +46 703 1923 96. 

This is the only i could come up with so far. On the other hand i could also go another way, by checking up on FA-18 C/D Hornet. It uses the same engine. Havent had so much time to dig into it yet. But yes i found out that there might be some problem with the engine-temp so far. Check the link, see if that might get you the answers you are searching for.   If you want answers fast, i recomend you contact the Cheif engineer above. But im not sure how truthful aswers you would get from him.
Title: Re: Gripen quality???
Post by: chacko on August 25, 2005, 02:48:05 PM
One should understand its lik any other vehicle. It will have quality and manufacture issues.
Title: Re: Gripen quality???
Post by: J.K Nilsson on October 15, 2005, 05:32:02 PM
Hi there!


Is this really the case and how does the Gripens engine really cope in hot conditions?

Any replys would be great!


The JAS 39 EBS has got  a WWC modification that allows the aircraft to operate in varius climates. The RM 12 operates at a higher temperature than the F404 due the higher output thrust. In high temperature climates every jet aircraft require longer runway to get airborne compared to colder climates. Since SAAF didn´t order brakes to the nose wheels i don´t think that take of is any problem i South Africa.

J.K Nilsson